Aplastic Anemia

About Aplastic Anemia

Aplastic anemia is a form of bone marrow failure. It is primarily a disease of children and younger adults but can occur at any age. At the Johns Hopkins Kimmel Cancer Center, patients with aplastic anemia are managed by experts with the Bone Marrow Failures Disorders Program. The bone marrow, a spongy tissue inside the bones, is the factory for all blood cell lines -- red cells, white cells, and platelets. These cells are critical to supplying oxygen and nourishment to other tissues and organs, fighting infection, and clotting the blood. Typically, as old blood cells die off naturally, they are replaced by new blood cells formed in the bone marrow. In aplastic anemia, the bone marrow does not produce new cells, leaving the body susceptible to bleeding and infection.

Aplastic anemia can be acquired or inherited, although most cases are acquired. Inherited forms usually present during the first decade of life. Acquired forms are believed to result from an immune-mediated attack directed at hematopoietic progenitor cells --- the stem cells that turn into different types of blood cells. Immune system white blood cells called T cells target the hematopoietic stem cells and cause cell death. Researchers have discovered that most cases of severe aplastic anemia are autoimmune disorders in which the body’s immune system attacks its tissues and organs. They believe that autoreactive or abnormal immune cells known as lymphocytes suppress blood cell production and division. Although aplastic anemia is not a cancer, the treatment is often similar to therapies used for blood-forming cancers such as leukemias and lymphomas. Watch a video to learn more about Aplastic Anemia

Risk Factors

A number of environmental factors, including drugs, chemicals, radiation, and viruses, have been implicated as triggers for the immune attack leading to aplastic anemia. In most cases, the cause of aplastic anemia cannot be identified. This is called idiopathic.

Symptoms

In patients with aplastic anemia, the quantity of each of the three blood cell types is much lower than normal, which leads to symptoms that cause a physician to suspect the disease. These symptoms are unexplained infections (due to fewer white blood cells), unexpected bleeding (due to fewer platelets) and fatigue (due to fewer red blood cells). Patients identified early through abnormalities seen in routine laboratory testing may have no symptoms.

Overall, the most common symptoms of aplastic anemia include:

Significant fatigue or weakness

Bruising or bleeding easily

Shortness of breath

Recurring infections and/or flu-like symptoms

The appearance of small red dots on the skin that indicates bleeding under the skin

Headache

Fever due to infection

Diagnosis

Severe aplastic anemia is a serious disorder requiring prompt medical attention. To diagnose aplastic anemia, physicians must examine the cells of the bone marrow and blood under a microscope. To do this, they will likely perform blood and laboratory tests as well as a bone marrow aspiration and biopsy. During this test, a sample of bone marrow is removed from the hipbone with a special needle under local anesthetic. The physician will check the number of blood cells, including white cells known as neutrophils, clotting cells known as platelets, and young, regenerating red cells known as reticulocytes. Your doctor may also study kidney function or order other associated tests. HLA-typing, a laboratory blood test, is usually performed to ensure that patients receive immune system-compatible blood and marrow products during treatment.

Ideally, the diagnosis should be made by an experienced physician at a bone marrow failure specialty center.

Classification

Classifying aplastic anemia depends on the numbers of blood cells present in the blood tests and bone marrow biopsy. Aplastic anemia may be classified as moderate (MAA), severe (SAA), or very severe (VSAA). SAA and VSAA are usually treated aggressively while MAA can be observed in appropriate situations.

Treatments

The decision to treat patients with aplastic anemia is based on disease severity. Treatment with immune system-suppressing therapy or a stem cell (bone marrow) transplant is necessary for patients with severe aplastic anemia while there is no standard of care for moderate aplastic anemia. Severe aplastic anemia patients younger than 40 years old with a blood-matched sibling are usually treated by a bone marrow transplant, while those over 40 or without a blood-matched sibling are usually treated by drug therapy.

High-dose Cyclophosphamide Physician-scientists at Johns Hopkins developed a treatment using high doses of the chemotherapy drug cyclophosphamide, without bone marrow transplantation, to achieve long-lasting, complete remissions in some patients with severe aplastic anemia. The drug can rid the body of the cells that cause aplastic anemia without destroying key blood and bone marrow-forming stem cells.

Blood Transfusion Platelet transfusions are the first course of treatment for any aplastic anemia patient who is severely deficient in these blood cells. The transfusions reduce the high risk these patients have of suffering a fatal hemorrhage. Transfusions of red blood cells can help combat the fatigue and shortness of breath experienced by aplastic anemia patients. The process may quickly stabilize aplastic anemia patients with severe blood cell deficiencies, but it is very rare for a patient to achieve a long-term recovery using this form of treatment alone.

During a transfusion, a technician will hang a bag containing the blood product you are receiving from a pole, then insert a narrow tube into a blood vessel in your arm. The healthy blood from a donor will drip from the bag through the tube and into your vein. The procedure usually takes about one to two hours, depending on what blood component(s) you are receiving. Most people do not experience side effects from the procedure, although possible side effects include fever, allergic reaction or infection.

Bone Marrow Transplantation Aplastic anemia was one of the first diseases for which bone marrow transplantation was found to be effective. In this therapy, the patient's non-functioning bone marrow is destroyed with drugs and/or radiation and replaced with donor bone marrow from a compatible donor, usually a sibling or other family member. The donor marrow is given intravenously to the patient and travels to the bone regenerating blood cells. When successful, bone marrow transplant is often a cure for aplastic anemia with few incidences of relapse. However, it is a very intensive therapy, and serious immune complications and infections are not unusual. Other non-life-threatening effects of bone marrow transplantation include sterility and temporary hair loss. Patients under age 40 are the best candidates. Cure rates decline significantly in those over 40.

Bone marrow transplants from alternative donors (unrelated or mismatched donors) are usually reserved for severe aplastic anemia or very severe aplastic anemia patients who have not responded to immunosuppressive drug therapy first. However, this may change in the future.

Medical Therapy In some patients, bone marrow transplantation may not be an option.. Age, other health-related factors, or the inability to find a compatible donor may make a transplant too risky. Immunosuppressive drug therapy with anti-thymocyte globulin (ATG) and cyclosporine may be recommended for these patients. While drug therapy is not a cure for aplastic anemia, it may partially restore blood cell production. However, up to 50 percent of patients relapse or develop other blood-forming malignancies or disorders. The medications also may be given before a stem cell transplant. Side effects include fever, high blood pressure and kidney problems.

Additionally there has been a single new drug approved for SAA in the past 30 years: eltrombopag. Unfortunately, this drug has limitations: There is only a 20% response rate and even in those who respond, there remains the potential for relapse. This is currently an option for patients in whom bone marrow transplantation may not be possible.

Supportive care Supportive care and long term follow-up are imperative in the management of aplastic anemia. A central venous catheter – a tube that carries medicines to a vein in the chest – may be helpful for aplastic anemia patients who require frequent transfusions or infused medications. Patients with deficiencies in certain blood elements may require urgent support with infused blood products, such as packed red blood cells to correct or avoid cardiopulmonary complications. The goal of platelet therapy should be to maintain a platelet count to prevent spontaneous bleeding.

Because fungal and bacterial infections are a major cause of death in patients with severe aplastic anemia, patients may require therapy with antibiotics, or with antiviral or antifungal agents.